1 /* 2 * Author: Tatu Ylonen <ylo@cs.hut.fi> 3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 4 * All rights reserved 5 * 6 * As far as I am concerned, the code I have written for this software 7 * can be used freely for any purpose. Any derived versions of this 8 * software must be clearly marked as such, and if the derived work is 9 * incompatible with the protocol description in the RFC file, it must be 10 * called by a name other than "ssh" or "Secure Shell". 11 * 12 * 13 * Copyright (c) 1999 Niels Provos. All rights reserved. 14 * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 */ 36 37 #include "includes.h" 38 RCSID("$OpenBSD: cipher.c,v 1.68 2004/01/23 19:26:33 hshoexer Exp $"); 39 40 #include "xmalloc.h" 41 #include "log.h" 42 #include "cipher.h" 43 44 #include <openssl/md5.h> 45 46 #if OPENSSL_VERSION_NUMBER < 0x00907000L 47 extern const EVP_CIPHER *evp_rijndael(void); 48 extern void ssh_rijndael_iv(EVP_CIPHER_CTX *, int, u_char *, u_int); 49 #endif 50 extern const EVP_CIPHER *evp_ssh1_bf(void); 51 extern const EVP_CIPHER *evp_ssh1_3des(void); 52 extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int); 53 extern const EVP_CIPHER *evp_aes_128_ctr(void); 54 extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int); 55 56 struct Cipher { 57 char *name; 58 int number; /* for ssh1 only */ 59 u_int block_size; 60 u_int key_len; 61 const EVP_CIPHER *(*evptype)(void); 62 } ciphers[] = { 63 { "none", SSH_CIPHER_NONE, 8, 0, EVP_enc_null }, 64 { "des", SSH_CIPHER_DES, 8, 8, EVP_des_cbc }, 65 { "3des", SSH_CIPHER_3DES, 8, 16, evp_ssh1_3des }, 66 { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, evp_ssh1_bf }, 67 68 { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, EVP_des_ede3_cbc }, 69 { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, EVP_bf_cbc }, 70 { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, EVP_cast5_cbc }, 71 { "arcfour", SSH_CIPHER_SSH2, 8, 16, EVP_rc4 }, 72 #if OPENSSL_VERSION_NUMBER < 0x00907000L 73 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, evp_rijndael }, 74 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, evp_rijndael }, 75 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, evp_rijndael }, 76 { "rijndael-cbc@lysator.liu.se", 77 SSH_CIPHER_SSH2, 16, 32, evp_rijndael }, 78 #else 79 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, EVP_aes_128_cbc }, 80 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, EVP_aes_192_cbc }, 81 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, EVP_aes_256_cbc }, 82 { "rijndael-cbc@lysator.liu.se", 83 SSH_CIPHER_SSH2, 16, 32, EVP_aes_256_cbc }, 84 #endif 85 { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, evp_aes_128_ctr }, 86 { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, evp_aes_128_ctr }, 87 { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, evp_aes_128_ctr }, 88 { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, EVP_acss }, 89 90 { NULL, SSH_CIPHER_ILLEGAL, 0, 0, NULL } 91 }; 92 93 /*--*/ 94 95 u_int 96 cipher_blocksize(const Cipher *c) 97 { 98 return (c->block_size); 99 } 100 101 u_int 102 cipher_keylen(const Cipher *c) 103 { 104 return (c->key_len); 105 } 106 107 u_int 108 cipher_get_number(const Cipher *c) 109 { 110 return (c->number); 111 } 112 113 u_int 114 cipher_mask_ssh1(int client) 115 { 116 u_int mask = 0; 117 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */ 118 mask |= 1 << SSH_CIPHER_BLOWFISH; 119 if (client) { 120 mask |= 1 << SSH_CIPHER_DES; 121 } 122 return mask; 123 } 124 125 Cipher * 126 cipher_by_name(const char *name) 127 { 128 Cipher *c; 129 for (c = ciphers; c->name != NULL; c++) 130 if (strcasecmp(c->name, name) == 0) 131 return c; 132 return NULL; 133 } 134 135 Cipher * 136 cipher_by_number(int id) 137 { 138 Cipher *c; 139 for (c = ciphers; c->name != NULL; c++) 140 if (c->number == id) 141 return c; 142 return NULL; 143 } 144 145 #define CIPHER_SEP "," 146 int 147 ciphers_valid(const char *names) 148 { 149 Cipher *c; 150 char *ciphers, *cp; 151 char *p; 152 153 if (names == NULL || strcmp(names, "") == 0) 154 return 0; 155 ciphers = cp = xstrdup(names); 156 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0'; 157 (p = strsep(&cp, CIPHER_SEP))) { 158 c = cipher_by_name(p); 159 if (c == NULL || c->number != SSH_CIPHER_SSH2) { 160 debug("bad cipher %s [%s]", p, names); 161 xfree(ciphers); 162 return 0; 163 } else { 164 debug3("cipher ok: %s [%s]", p, names); 165 } 166 } 167 debug3("ciphers ok: [%s]", names); 168 xfree(ciphers); 169 return 1; 170 } 171 172 /* 173 * Parses the name of the cipher. Returns the number of the corresponding 174 * cipher, or -1 on error. 175 */ 176 177 int 178 cipher_number(const char *name) 179 { 180 Cipher *c; 181 if (name == NULL) 182 return -1; 183 c = cipher_by_name(name); 184 return (c==NULL) ? -1 : c->number; 185 } 186 187 char * 188 cipher_name(int id) 189 { 190 Cipher *c = cipher_by_number(id); 191 return (c==NULL) ? "<unknown>" : c->name; 192 } 193 194 void 195 cipher_init(CipherContext *cc, Cipher *cipher, 196 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen, 197 int encrypt) 198 { 199 static int dowarn = 1; 200 const EVP_CIPHER *type; 201 int klen; 202 203 if (cipher->number == SSH_CIPHER_DES) { 204 if (dowarn) { 205 error("Warning: use of DES is strongly discouraged " 206 "due to cryptographic weaknesses"); 207 dowarn = 0; 208 } 209 if (keylen > 8) 210 keylen = 8; 211 } 212 cc->plaintext = (cipher->number == SSH_CIPHER_NONE); 213 214 if (keylen < cipher->key_len) 215 fatal("cipher_init: key length %d is insufficient for %s.", 216 keylen, cipher->name); 217 if (iv != NULL && ivlen < cipher->block_size) 218 fatal("cipher_init: iv length %d is insufficient for %s.", 219 ivlen, cipher->name); 220 cc->cipher = cipher; 221 222 type = (*cipher->evptype)(); 223 224 EVP_CIPHER_CTX_init(&cc->evp); 225 if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv, 226 (encrypt == CIPHER_ENCRYPT)) == 0) 227 fatal("cipher_init: EVP_CipherInit failed for %s", 228 cipher->name); 229 klen = EVP_CIPHER_CTX_key_length(&cc->evp); 230 if (klen > 0 && keylen != klen) { 231 debug2("cipher_init: set keylen (%d -> %d)", klen, keylen); 232 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0) 233 fatal("cipher_init: set keylen failed (%d -> %d)", 234 klen, keylen); 235 } 236 if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0) 237 fatal("cipher_init: EVP_CipherInit: set key failed for %s", 238 cipher->name); 239 } 240 241 void 242 cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) 243 { 244 if (len % cc->cipher->block_size) 245 fatal("cipher_encrypt: bad plaintext length %d", len); 246 if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0) 247 fatal("evp_crypt: EVP_Cipher failed"); 248 } 249 250 void 251 cipher_cleanup(CipherContext *cc) 252 { 253 if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0) 254 error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed"); 255 } 256 257 /* 258 * Selects the cipher, and keys if by computing the MD5 checksum of the 259 * passphrase and using the resulting 16 bytes as the key. 260 */ 261 262 void 263 cipher_set_key_string(CipherContext *cc, Cipher *cipher, 264 const char *passphrase, int encrypt) 265 { 266 MD5_CTX md; 267 u_char digest[16]; 268 269 MD5_Init(&md); 270 MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase)); 271 MD5_Final(digest, &md); 272 273 cipher_init(cc, cipher, digest, 16, NULL, 0, encrypt); 274 275 memset(digest, 0, sizeof(digest)); 276 memset(&md, 0, sizeof(md)); 277 } 278 279 /* 280 * Exports an IV from the CipherContext required to export the key 281 * state back from the unprivileged child to the privileged parent 282 * process. 283 */ 284 285 int 286 cipher_get_keyiv_len(const CipherContext *cc) 287 { 288 Cipher *c = cc->cipher; 289 int ivlen; 290 291 if (c->number == SSH_CIPHER_3DES) 292 ivlen = 24; 293 else 294 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp); 295 return (ivlen); 296 } 297 298 void 299 cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len) 300 { 301 Cipher *c = cc->cipher; 302 int evplen; 303 304 switch (c->number) { 305 case SSH_CIPHER_SSH2: 306 case SSH_CIPHER_DES: 307 case SSH_CIPHER_BLOWFISH: 308 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); 309 if (evplen == 0) 310 return; 311 if (evplen != len) 312 fatal("%s: wrong iv length %d != %d", __func__, 313 evplen, len); 314 #if OPENSSL_VERSION_NUMBER < 0x00907000L 315 if (c->evptype == evp_rijndael) 316 ssh_rijndael_iv(&cc->evp, 0, iv, len); 317 else 318 #endif 319 if (c->evptype == evp_aes_128_ctr) 320 ssh_aes_ctr_iv(&cc->evp, 0, iv, len); 321 else 322 memcpy(iv, cc->evp.iv, len); 323 break; 324 case SSH_CIPHER_3DES: 325 ssh1_3des_iv(&cc->evp, 0, iv, 24); 326 break; 327 default: 328 fatal("%s: bad cipher %d", __func__, c->number); 329 } 330 } 331 332 void 333 cipher_set_keyiv(CipherContext *cc, u_char *iv) 334 { 335 Cipher *c = cc->cipher; 336 int evplen = 0; 337 338 switch (c->number) { 339 case SSH_CIPHER_SSH2: 340 case SSH_CIPHER_DES: 341 case SSH_CIPHER_BLOWFISH: 342 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); 343 if (evplen == 0) 344 return; 345 #if OPENSSL_VERSION_NUMBER < 0x00907000L 346 if (c->evptype == evp_rijndael) 347 ssh_rijndael_iv(&cc->evp, 1, iv, evplen); 348 else 349 #endif 350 if (c->evptype == evp_aes_128_ctr) 351 ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen); 352 else 353 memcpy(cc->evp.iv, iv, evplen); 354 break; 355 case SSH_CIPHER_3DES: 356 ssh1_3des_iv(&cc->evp, 1, iv, 24); 357 break; 358 default: 359 fatal("%s: bad cipher %d", __func__, c->number); 360 } 361 } 362 363 #if OPENSSL_VERSION_NUMBER < 0x00907000L 364 #define EVP_X_STATE(evp) &(evp).c 365 #define EVP_X_STATE_LEN(evp) sizeof((evp).c) 366 #else 367 #define EVP_X_STATE(evp) (evp).cipher_data 368 #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size 369 #endif 370 371 int 372 cipher_get_keycontext(const CipherContext *cc, u_char *dat) 373 { 374 Cipher *c = cc->cipher; 375 int plen = 0; 376 377 if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { 378 plen = EVP_X_STATE_LEN(cc->evp); 379 if (dat == NULL) 380 return (plen); 381 memcpy(dat, EVP_X_STATE(cc->evp), plen); 382 } 383 return (plen); 384 } 385 386 void 387 cipher_set_keycontext(CipherContext *cc, u_char *dat) 388 { 389 Cipher *c = cc->cipher; 390 int plen; 391 392 if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { 393 plen = EVP_X_STATE_LEN(cc->evp); 394 memcpy(EVP_X_STATE(cc->evp), dat, plen); 395 } 396 } 397